Helicopter rotor systems with pressure jets are known. Two of the most common types operate on hot and cold cycle principles to drive the gas production, distribution and flight characteristics. In the hot-cycle type turbine gas is produced at an output of about 1200 degrees Fahrenheit (F.degree.) which can impact severely on rotor components. The cold-cycle type of pressure-jet system is the type most investigated. With the cold-cycle type an engine drives an air compressor to provide thrust. This in effect is two engines (engine and compressor) which results in accompanying losses, lower payload, etc.
The present invention relates to a warm-cycle type of a fan-jet turbine whose gas temperature exhaust is about 480 degrees Fahrenheit (F.degree.) which provides for a unique circular plenum that interfaces with several (e.g., ten) hollow rotor blades at its perimeter. This new plenum design replaces almost half of the inner conventional rotor blade span with a similar to manufacture blade attached by a flapping hinge. As gas pressure is proportionally exhausted aft by dump valve arrangement to move the craft forward, the plenum becomes a lifting body that unloads the blades and supports the entire machine permitting its acceleration to the limits of the blade tip compressibility. The plenum causes a gyroscopic effect to occur providing for a very air stable helicopter which is completely free of icing regardless of weather conditions.